1. Field of the Invention
The present invention relates to a method of measuring image-sticking phenomenon of a display. More particularly, the present invention relates to a method which may accurately measure an image-sticking level of a display.
2. Description of Related Art
Image-sticking is a phenomenon that an image or an outline of a previous static image appears in a next frame. Namely, when a static image is displayed on a screen for a relatively long time, it remains visible when the image is changed. Generally, the image-sticking phenomenon is observed by human eyes due to excessive brightness or color difference between an image-stick region and a non-image-stick region.
Presently, the criterion and measuring standard of image-sticking levels are still not standardized due to improper measuring methods or impossible implementation of the measuring methods. The existing methods are described as follows.
The method provided by US Pub. No. 2003/0214586 is employed to measure the image-sticking levels by applying a charge coupled device (CCD). However, since the CCD cannot accurately simulate a sense of human eyes and cannot effectively quantify the sense, the method cannot be practically applied.
The method provided by U.S. Pat. No. 6,791,520 is employed to measure the image-sticking levels according to a brightness difference. However, this method is susceptible to an interference of the color difference, and since the image-sticking phenomenon relates to an obvious degree of a boundary between different image-stick regions, the image-sticking level cannot be determined according to the brightness difference. Therefore, this measuring method is likewise not practically applicable.
The method provided by US Pub. No. 2002/0097395 is employed to measure the image-sticking levels by changing gray levels based on a variation of voltages. However, this measuring method can only be applied to a liquid crystal display (LCD). Moreover, since a resistance on a test panel has to be changed for further subdivision of the voltages on an original γresistance curve, this measurement method cannot actually be applied on the products.
The method provided by U.S. Pat. No. 6,590,411 is employed to measure the image-sticking level according to the variation of capacitances. This measurement method can only be applied to the LCD. Moreover, since a plurality of parasitic capacitances generated in a panel structure may interfere a measurement result, this measurement method can only be applied a test panel having a simple structure, and the measuring result cannot directly be applied to the products.